Apparatus for welding,fusing or heating workpiece utilizing energy of a light beam

ABSTRACT

An apparatus for welding, fusing or heating a workpiece utilizing the energy of a light beam comprising an eliptical mirror, a light source of high-temperature are disposed at a first focus of the elliptical mirror and means for holding the workpiece at a second focus of the elliptical mirror. In the apparatus, cooling means is disposed adjacent to the elliptical mirror for cooling the light source.

United States Patent [191 Yoshizumi et a1.

APPARATUS FOR WELDING, FUSING OR HEATING WORKPIECE UTILIZING ENERGY OF A LIGHT BEAM Inventors: Shuzo Yoshizumi, Takarazuka;

Yoshimitsu Matsumoto, Toyonaka, both of Japan Assignee:

Filed:

Matsushita Electric Industrial Co.

Nov. 24, 1972 Appl. No.: 309,000

Foreign Application Priority Data Nov. 26, 1971 Japan 46-95472 Dec. 9, 1971 Japan 46-99980 Dec. 11, 1971 Japan 46-100350 Dec. 11, 1971 Japan 46-100351 Dec. 17, 1971 Japan 46-103060 US. Cl. 219/85, 219/347 Int. Cl 323k 1/04 Field of Search 219/85, 347, 348, 349,

[451 May 21, 1974 [56] References Cited UNITED STATES PATENTS 3,621,198 11/1971 Herrich 219/349 3,486,004 12/1969 Morrone 219/347 X 1,802,407 4/1931 Danninger et a1. 219/348 UX 3,103,574 9/1963 Chellis et a1 219/34 3,709,414 1/1973 Dahlberg et a1. 219/347 FOREIGN PATENTS OR APPLICATIONS 870,061 6/1961 Great Britain 219/349 Primary Examiner-C. L. Albritton Attorney, Agent, or FirmStevens, Davis, Miller & Mosher [57] ABSTRACT An apparatus for welding, fusing or heating a workpiece utilizing the energy of a light beam comprising an eliptical mirror, a light source of high-temperature are disposed at a first focus of the elliptical mirror and means for holding the workpiece at a second focus of the elliptical mirror. In the apparatus, cooling means is disposed adjacent to the elliptical mirror for cooling the light source.

5 Claims, 11 Drawing Figures IATENTEDHAY 2 I974 SHEET 1 BF 4 FIG. 3

PATENTEDMAYZI m 3.812.318 SMU 3 BF 4 FIG. 6b

APPARATUS FOR WELDING, FUSING OR HEATING WORKPIECE UTILIZING ENERGY OF A LIGHT BEAM This invention relates to an apparatus for welding, fusing or heating workpieces by the energy of light, and more particularly to means for extending the service life of the apparatus, reducing the overall size of the apparatus and improving the efficiency of the apparatus.

Recently, attention is being increasingly directed to apparatus for welding, fusing or heating metals and other materials by condensing the energy of light emitted from a stable source of high-temperature radiation such as an arc lamp. However, apparatus of this kind proposed hitherto have been defective in that a large temperature rise tends to occur at various portions of the apparatus thereby shortening the service life and deteriorating the operating efficiency of the apparatus.

It is a primary object of the present invention to provide a novel and improved apparatus of this kind in which cooling means are provided for obviating such a defect.

In an apparatus utilizing the energy of light, a lamp emitting a high-temperature light is generally disposed at or adjacent to a first focus of an elliptical mirror and the energy of light is concentrated into a second focus of the mirror for welding, fusing or heating workpieces. of metal or like material. In such an apparatus, very satisfactory results can be obtained when the ratio b/a between the second focal distance b and the first focal distance a of the elliptical mirror is selected to be less than 8. Further, it is also an essential condition that the depth of the elliptical mirror be greater than the first focal distance a of the mirror. In order to reduce the overall size of the elliptical mirror while satisfying such a condition, it is necessary to shorten the distance between the first and second focuses. For that reason, a part of the lamp has to be disposed adjacent to the second focuses, accordingly the lamp is inevitably heated, for there is the problem that the life of the lamp becomes shorter and also many other problems may arise.

In accordance with the present invention, there is provided an apparatus for welding, fusing or heating a workpiece utilizing the energy of light comprising an elliptical mirror, a light source of high-temperature radiation disposed at or adjacent to a first focus of said elliptical mirror, means for holding the workpiece at or adjacent to a second focus of said elliptical mirror, cooling fluid injecting means disposed adjacent to said elliptical mirror for injecting a cooling fluid for cooling said light source, and cooling fluid discharging means disposed adjacent to said elliptical mirror for discharging the cooling fluid.

The above and other objects, features and advantages of the present invention will be apparent from the following detailed description taken in conjunction with the accompanying drawing, in which:

FIG. 1 is a schematic sectional view showing the structure of an embodiment of the present invention;

FIG. 2 is a diagrammatic view showing three cooling fluid injection ports arranged in directions tangential to the outer periphery of the electrode portion shown in FIG. 1;

FIG. 3 is a schematic sectional view showing the structure of another embodiment of the present invention for welding, fusing or heating workpieces by the energy of light;

FIG. 4 is a schematic sectional view showing the structure of a further embodiment of the present invention;

FIG. 5 is a graph showing the relation between the angle of incidence 0 and the index of reflection of light when light advances into atmospheric air from a glass member employed in the present invention;

FIGS. 6a, 6b and 6c are diagrammatic views illustrating the manner of determining by the angle of incidence 0 of light the shape of the glass member employed by the angle of incidence 6 of light in the present invention;

FIG. 7 is a graph showing temperature variations relative to time in a piror art apparatus of this kind;

FIG. 8 is a schematic perspective view showing principal arts of another embodiment of the present invention; and

FIG. 9 is a graph showing temperature variations and power consumption relative to time in the apparatus shown in FIG. 8.

Referring to FIG. 1 showing an embodiment of the present invention, an arc lamp S emitting a hightemperature light comprises an electrode portion R including electrodes and accessory parts. The lamp Sis combined with an elliptical mirror E having a first focus F and a second focus F and is disposed at or adjacent to the first focus F of the elliptical mirror E. At least two cooling fluid injection ports N are disposed at spaced positions between the first focus F and the second focus F of the elliptical mirror E with their openings directed toward the electrode portion R of the lamp S so as to direct a cooling fluid along a flow line LL. Thus, the molecules of the cooling fluid can impinge directly against the excessively heated portions of the lamp S.

Referring to FIG. 2, three such cooling fluid injection ports N are disposed in directions tangential to the outer periphery of the electrode portion R of the lamp S so that a spiral stream of cooling fluid can be produced and pass around the excessively heated portions of the lamp S for maintaining the temperature of the lamp S at a predetermined value. The cooling fluid having cooled the excessively heated portions of the lamp S is finally forcibly discharged from a discharge port EX provided at the center of the bottom of the elliptical mirror E. In the course of discharge of the cooling fluid from the discharge port EX, the molecules of the cooling fluid impinge against the reflecting surface of the elliptical mirror E to prevent undesirable appearance of an excessive temperature gradient across the elliptical reflector E.

The apparatus having a structure as shown in FIG. 1 provides the following advantages among others:

1. The electrode portion (including the electrodes and accessory parts) and the portion of the hightemperature arc lamp extending from the position adjacent to the first focus F, toward the second focus F of the elliptical mirror as well as the space around these portions, can be cooled directly by a cooling medium, and thus, the service life of the high-temperature arc lamp can be remarkably extended.

2. The cooling efficiency can be remarkably improved due to the fact that the cooling fluid is directed to the most severely heated portions of the arc lamp and to the space around such portions in the welding, fusing or heating apparatus.

3. Due to the provision of the cooling fluid discharge port at the bottom of the elliptical mirror, the mirror is prevented from having an occurrence of an excessive local temperature gradient so that the service life of the elliptical mirror can be extended.

Another embodiment of the present invention will be described with reference to FIG. 3. Referring to FIG. 3, an open-ended outer casing 1 is formed by a plate of metal or like material, and a bottom plate 2 is secured to the lower end of the outer casing l. A partition plate 3 is disposed intermediate between the upper and lower ends of the outer casing I, and an elliptical mirror 4 is mounted to the lower surface of the partition plate 3 by means of a mounting plate 5 and bolts 6. A hightemperature are emitting lamp 7 is disposed at or adjacent to a first focus F of the elliptical mirror 4.

An opening 8 is provided in the bottom of the elliptical mirror 4 for supplying a cooling fluid into the internal space of the elliptical mirror 4.

The cooling fluid is supplied from a cooling fluid supply means 9 such as a blower disposed on the partition plate 3. The cooling fluid supplied from the supplying means 9 is injected toward the lamp 7 through an injection nozzle 10 fitted in the bottom opening 8 of the elliptical mirror 4 for cooling the lamp 7. The cooling fluid having cooled the lamp 7 flows through the space between the bottom plate 2 and the elliptical mirror 4 to be discharged from the outer casing l by a fluid discharging means 11 such as a sirocco fan disposed on the bottom plate 2. A light shading plate 12 is movably disposed on the bottom plate 2 in the path of light so as to open or close an opening of the bottom plate 2.

With such a structure, it has been experimentarily proved that the cooling effect varies greatly depending on the direction of the fluid suction port of the fluid discharging means ll. It has been found that the cooling can be attained most effectively when the fluid suction port of the fluid discharging means 11 is directed toward the lower end portion of the lamp 7 extending from the position adjacent to the first focus F, toward the second focus F, of the elliptical mirror 4. It has further been found that the cooling can be attained with better efficiency when the cooling fluid supplying means 9 is isolated completely from the hightemperature are lamp 7 and elliptical mirror 4 by the partition plate 3.'A test carried out with an apparatus having an arrangement as above described has proved that the temperature rise at a point in the vicinity of the gas enclosing envelope portion of, for example, a 5 KW high-temperature arc lamp can be suppressed to about 100 to 120 C and the service life of the arc lamp can be remarkably extended, whereas a large temperature rise of from about 200 to 250 C occurs at such a point in a similar apparatus when it is not arranged in the manner described above. Further, the total volume of the former apparatus is of the order of 1.0 x 10 cm and is thusvery small, whereas the total volume of the latter apparatus including the cooling means is larger than 5.0 x 10 cm.

It will be understood that the apparatus of the present and the apparatus is small in size and can be easily handled.

Referring to FIG. 4 showing a further embodiment of the present invention, an elliptical mirror M is fixedly mounted by a fixing means 23 in a hermetically sealed outer casing 25, and a cooling fluid supplying duct 21 is connected to a bottom opening of the elliptical mirror M. A high-temperature arc emitting lamp S is disposed within the elliptical mirror M at or adjacent to a first focus F of the elliptical mirror M, and its position is adjustable by adjusting means shown by the reference numeral 22. A member A covers sealingly a bottom opening of the casing 25 and is fixed in such position by a fixing ring 24. This member A is such that it transmits the energy of light but does not allow for flow-out of a cooling fluid therethrough. The light energy transmitting member A may be made of a material such as heat-resisting glass or plastic. The casing 25 is provided with a cooling fluid discharging means (not shown) which discharges to the exterior the cooling fluid having cooled the source of high-temperature radiation. A workpiece W is disposed at or adjacent to a second focus F of the elliptical mirror M. Due to the above arrangement, the cooling fluid having cooled the high-temperature arc lamp S does not impinge against the workpiece W by being intercepted by the light energy transmitting member A of heat-resisting glass.

The apparatus of the present invention having a structure as shown in FIG. 4 provides the following advantages among others:

I. The working efficiency is improved and stable working can be achieved due to the fact that the molecules of the cooling fluid do not impinge against the workpiece.

2. Inclusion of the molecules of the cooling fluid in the workpiece can be avoided thereby providing a welded, fused or heated zone of high purity.

3. Due to the fact that the high-temperature arc lamp and elliptical mirror are completely isolated from the workpiece, active gases emanating from the workpiece as well as dust particles are prevented from attaching to the arc lamp and elliptical mirror, and the service life of the arc lamp and elliptical mirror can be extended.

The shape of the light energy transmitting and cooling fluid intercepting member A of heat-resisting glass should be suitably selected to suit the apparatus of the present invention which utilizes the energy of light for welding, fusing and heating workpieces.

When a beam of light transmitted through a glass plate emerges from the glass plate into atmospheric air, the light beam is reflected at the boundary between the glass plate and the atmospheric air. The index of reflection of' the light at the glass surface in the above case becomes abruptly large when the angle of incidence 0 exceeds 30 as shown in FIG. 5. Therefore, by suitably selecting the shape of the glass member A so as to reduce the angle of incidence 6 to less than 30 as shown in FIG. 6a, the loss of the light energy due to reflection at the glass surface can be minimized.

Preferred means for attaining this purpose will be described in more detail. Referring to FIG. 6a, light is transmitted through the glass member A to be concentrated on a point 0 along a path L0. The angle of incidence 6 is determined by the contour of the surface f opposite to the first focus F, of the elliptical mirror M and by the contour of the surface f, opposite to the second focus F of the elliptical mirror M. Suppose that n is the refractive index, the glass member A and 4) is the angle defined between the light path L0 and the line Nf, normal to the surface f, at the intersection A between the light path OL and the surface f,. Then, it is apparent that the relation sin 4) n sin 6 holds between the angle 41 and the angle of incidence 6. When the angle of incidence 6 is selected to have a suitable value less than 30, the angle 4) is determined and the contour of the surface f is determined. Suppose further that -y is the angle defined between the light path OL inside of the glass member A and the line Nf normal to the surface f at the intersection B between the light path 0L and the surface f2, and 8 is the angle defined between the light path 0L outside of the glass member A and the normal Nf Then, it is apparent that the relation sin 8 n sin 'y holds between the angles 8 and -y. The angle is determined so that the light path OL outside of the surface f of the glass member A coincides substantially with the light path which is followed by the light in the case in which the glass member A is not present in the path of the light. The determination of the angle y at such a value determines the contour of the surface f, of the glass member A. In this manner, the shape of the galss member A can be determined. FIG. 6a shows the surface shape in which both the surface f, and f, are concentric around a point Os. FIG. 6b shows the surface shape in which both the surface f, and f are portions of prolate spheroids. FIG. 60 shows the surface shape comprising a combination of flat planes. In the present invention, the refractive index n of the glass member A is preferably of the order of 1.45 to 1.7.

The use of the glass member having various surface shapes as shown in FIGS. 6a, 6b and 6c is advantageous in that undesirable reflection of the energy of light at the boundary between the glass member and the atmospheric air can be reduced to a minimum in addition to the advantages described with reference to the embodiment shown in FIG. 4.

In a prior art welding, fusing or heating apparatus utilizing the energy of light emitted from an arc lamp, a constant current or voltage is continuously supplied to the lamp for energizing the lamp and a light shading plate is suitably actuated to control the supply of the energy of light to a workpiece. However, with such a method, a large temperature rise occurs not only in the lamp but also at various portions of the apparatus as shown in FIG. 7 thereby shortening the service life of the lamp and deteriorating the welding, fusing or heating ability of the apparatus. In FIG. 7, the lamp is energized at time Q, and working is carried out for a period of time T,, between the two periods of times '1, representing preparatory steps, before and after one working step. The curves 0, b and c in FIG. '7 represent temperature variations at the lamp mounting portion, light condensing system and light shading plate respectively.

Another embodiment of the present invention shown in FIG. 8 eliminates prior art defects as above described. Referring to FIG. 8, an arc lamp is combined with an elliptical mirror and the light emitted from the lamp is condensed for welding, fusing or heating a workpiece. In this apparatus, a light shading plate 31 is provided for controlling the energy of light emitted from the lamp. The light shading plate 31 is freely movable in a direction shown by the arrow and is connected to a transducer 32. The transducer 32 detects the movement of the light shading plate 31 and transduces the mechanical motion of the light shading plate 31 into an electrical signal. The electrical signal delivered from the transducer 32 is applied to a control device 33 which controls the current or voltage supplied to the lamp. Thus, the current or voltage supplied to the lamp can be automatically controlled. Thus, the undesirable temperature rise at various portions of the apparatus can be remarkably reduced. FIG. 9 shows, by way of example, temperature variations at various portions of the apparatus when the high-temperature radiation emitting lamp is energized at room temperature of 20 C and working is repeatedly carried out for a period of time T of about 10 minutes interposed between the two periods of times T of about 5 minutes representing preparatory steps prior to and subsequent to the working. The curves a, b and c in FIG. 9 represent temperature variations at the lamp mounting portion, light .condensing system and light shading plate 31 respectively. The highest temperatures appearing at the lamp mounting portion, light condensing system and light shading plate 31 are about 100 C, 50 C and C, respectively, which are about one-half or one-third of the values observed with the prior art apparatus of this kind. Further, large power consumption appears only during the working period of time and the total power consumption can be reduced to about two-thirds of the value required for the prior art apparatus.

It will be understood from the foregoing description that the undesirable temperature rise at various portions of the apparatus according to the present invention can be reduced remarkably and this provides the advantage in that the service life of the apparatus, especially the service life of the high-temperature radiation emitting lamp can be remarkably extended. Further, the present invention provides a remarkable economical advantage in that the power consumption can be reduced to about 60 percent of prior requirements. Furthermore, by virtue of the low overall temperature rise, welding, fusing or heating can be satisfactorily carried out and the apparatus is reliably serviceable for operations over an extended period of time.

What is claimed is:

1. Apparatus for welding, fusing or heating a workpiece by irradiating said workpiece with electromagnetic radiation, comprising: an elliptical mirror reflecting housing; a source of light energy located at a first focus of said mirror; means mounting said workpiece at a second focus of said mirror spaced from said first focus', a light energy permeable partition disposed between said tirst and second foci; cooling fluid injecting means located adjacent said mirror for injecting cooling fluid into said housing for cooling said source of light energy; and cooling fluid discharging means located adjacent said mirror for discharging cooling fluid from said housing; said injecting means and discharging means being separated from said second focus by said partition to prevent said cooling fluid from reaching said second focus.

2. The apparatus according to claim 1, further comprising an outer casing housing said mirror and discharging means, said casing having an opening therein in the path between said first and second foei; said partition being located in said opening.

3. An apparatus for welding, fusing or heating a workpiece utilizing the energy of light, comprising: an

elliptical mirror; a light source lamp of hightemperature radiation disposed at a first focus of said elliptical mirror; means for setting the workpiece at a second focus of said elliptical mirror; cooling fluid injecting means disposed adjacent to said elliptical mirror for injecting a cooling fluid for cooling said light source; cooling fluid discharging means disposed adjacent to said elliptical mirror for discharging the cooling fluid; an outer casing having a bottom plate with an opening therein; and a partition plate disposed within said outer casing at a position intermediate between said bottom plate and the top wall of said casing; said elliptical mirror being provided with an opening in the bottom thereof and mounted on the lower surface of said partition plate, said cooling fluid injection means being mounted on said partition plate and connected to said opening of said elliptical mirror for injecting the cooling fluid through said opening for cooling said light source, and said cooling fluid discharging means being mounted on said bottom plate for discharging the cooling fluid having cooled said light source.

4. An apparatus as claimed in claim 3, further comprising light shading means freely and movably disposed between said first and second focuses of said elliptical mirror for controlling the energy of light concentrated by said elliptical mirror, control means for controlling the current or voltage supplied to said light source, and transducer means for transducing the mechanical motion of said light shading means into an electrical signal, said transducer means being connected to said control means for controlling the current or voltage supplied to said light source in response to the movement of said light shading means.

5. An apparatus for welding, fusing or heating a workpiece utilizing the energy of light comprising an elliptical mirror, a light source lamp of hightemperature radiation disposed at a first focus of said elliptical mirror, said mirror having a bottom surface portion on the other side of said first focus from said second focus, means for setting the workpiece at adjacent to a second focus of said elliptical mirror, at least two cooling fluid injecting means disposed at a position near said second focus between said first and second focuses in such a manner that their injection ports are directed toward said light source, and cooling fluid discharging means connected to an opening in the bottom of said elliptical mirror. 

1. Apparatus for welding, fusing or heating a workpiece by irradiating said workpiece with electromagnetic radiation, comprising: an elliptical mirror reflecting housing; a source of light energy located at a first focus of said mirror; means mounting said workpiece at a second focus of said mirror spaced from said first focus; a light energy permeable partition disposed between said first and second foci; cooling fluid injecting means located adjacent said mirror for injecting cooling fluid into said housing for cooling said source of light energy; and cooling fluid discharging means located adjacent said mirror for discharging cooling fluid from said housing; said injecting means and discharging means being separated from said second focus by said partition to prevent said cooling fluid from reaching said second focus.
 2. The apparatus according to claim 1, further comprising an outer casing housing said mirror and discharging means, said casing having an opening therein in the path between said first and second foci; said partition being located in said opening.
 3. An apparatus for welding, fusing or heating a workpiece utilizing the energy of light, comprising: an elliptical mirror; a light source lamp of high-temperature radiation disposed at a first focus of said elliptical mirror; means for setting the workpiece at a second focus of said elliptical mirror; cooling fluid injecting means disposed adjacent to said elliptical mirror for injecting a cooling fluid for cooling said light source; cooling fluid discharging means disposed adjacent to said elliptical mirror for discharging the cooling fluid; an outer casing having a bottom plate with an opening therein; and a partition plate disposed within said outer casing at a position intermediate between said bottom plate and the top wall of said casing; said elliptical mirror being provided with an opening in the bottom thereof and mounted on the lower surface of said partition plate, said cooling fluid injection means being mounted on said partition plate and connected to said opening of said elliptical mirror for injecting the cooling fluid through said opening for cooling said light source, and said cooling fluid discharging means being mounted on said bottom plate for discharging the cooling fluid having cooled said light source.
 4. An apparatus as claimed in claim 3, further comprising light shading means freely and movably disposed between said first and second focuses of said elliptical mirror for controlling the energy of light concentrated by said elliptical mirror, control means for controllIng the current or voltage supplied to said light source, and transducer means for transducing the mechanical motion of said light shading means into an electrical signal, said transducer means being connected to said control means for controlling the current or voltage supplied to said light source in response to the movement of said light shading means.
 5. An apparatus for welding, fusing or heating a workpiece utilizing the energy of light comprising an elliptical mirror, a light source lamp of high-temperature radiation disposed at a first focus of said elliptical mirror, said mirror having a bottom surface portion on the other side of said first focus from said second focus, means for setting the workpiece at adjacent to a second focus of said elliptical mirror, at least two cooling fluid injecting means disposed at a position near said second focus between said first and second focuses in such a manner that their injection ports are directed toward said light source, and cooling fluid discharging means connected to an opening in the bottom of said elliptical mirror. 